1. Field of the Invention
The present invention relates to a non-aqueous electrolytic battery module for use with an artificial satellite.
2. Description of the Related Art
An artificial satellite is usually equipped with a solar battery and a secondary battery. The solar battery supplies power to the artificial satellite during a solstice season (i.e., a period in which the solar battery is exposed to sunlight). During the solstice season, the secondary battery is charged by the solar battery. During an eclipse season (i.e., a period in which sunlight is blocked by the earth and the solar battery is not exposed to sunlight), the secondary battery supplies power to the artificial satellite.
A secondary battery provided in an artificial satellite is required to maintain stable charge/discharge cycles for over fifteen years. A nickel-hydrogen battery, for example, has conventionally been used as such a secondary battery. During a solstice season, i.e., a season during about 138 days in which the solar battery is always exposed to sunlight, the secondary battery is maintained in a fully charged state or a highly charged state by means of a float charging operation. During an eclipse season, i.e., a season during about 45 days in which the solar battery is eclipsed by the earth once a day, the secondary battery is discharged to supply power for the artificial satellite.
Recently, an attempt has been made to use a lithium battery including lithium-ion battery as a secondary battery to be provided in an artificial satellite. A lithium battery is deteriorated faster than is a nickel-hydrogen battery, when the batteries are maintained at high temperature. Further, the lithium battery is deteriorated much more than the nickel-hydrogen battery, when the batteries are maintained at a highly charged state. For these reasons, in a case where a lithium battery is maintained in the same managed temperature state or manage charged state as that in which a conventional nickel-hydrogen battery is maintained, the lithium battery is deteriorated faster than is the nickel-hydrogen battery. As a result, the discharging capacity of the lithium battery is diminished, and hence the lithium battery encounters difficulty in maintaining a stable charge/discharge characteristic.